Dungeons being an upcharge was always going to put it at a disadvantage. Especially given the general cost to visit the parks these days. However to essentially have it mothballed into a Scarefest only building (most likely result) is a bit meh. Always enjoyed a ride on Charlie, even if it was a bit crap.
If things were being replaced quickly then it wouldn't be a problem. Project Horizon has gone quiet so that corner of the park will continue to be a bit of a dead spot, and the lack of anything for kids too old for CBeebies but not at the height/level for Thirteen and others is just daft. Even if a 0.9m kid (I.e. my 2 year old) could go on Hex and Alty Mans, doesn't mean they are suitable attractions for the age content/theme wise. The RMT queues will continue to be insane.
With us still being in the CBeebies age range we're still in a decent position to visit. But in a few years? Would be a different story.